Fluid handling devices are becoming increasingly popular and there is an increased demand for fluid handling devices that are both portable and easy to use. Portable fluid handling devices are being used for applications such as home care, point of care testing, fuel cells, fragrance dispensers, etc. In order for a portable fluid handling device to be effective and efficient, it should be light weight, small in size, consume minimal power, operate with low noise, and be cost effective to manufacture. In many applications, it is also important that the fluid handling device provide an accurate and consistent fluid distribution. Therefore, it is necessary to incorporate an efficient fluid valve in the fluid handling device. In many aspects, the fluid valve characterizes the device's efficiency.
One solution of a portable valve that attempts to meet the above criteria is a miniature solenoid valve. The miniature solenoid valve however, is not as effective as originally anticipated. Solenoid valves are typically limited in size and in order to obtain adequate performance, a solenoid valve typically consumes a substantial amount of power. The power consumption of a solenoid valve, in some circumstances, is unacceptable, especially when using batteries as a power source, for example. The batteries may not be able to provide power to the valve for a sufficient length of time. Furthermore, in some applications, it may be desirable to retain the valve in a specific open or mid-point position. If this position requires continuous actuation of the solenoid, the valve will likely consume a substantial amount of power thereby increasing the cost associated with operating the valve.
Another solution has been the use of electrically actuated piezo valves. Some piezo valves operate using a closing arm that seals against a sealing shoulder when the piezo element is de-activated. These valves typically require a substantial amount of space to operate and may not always provide an adequate solution as they are subject to clogging when used with liquids that may dry around the orifice.
Another solution could be to use a stepper motor to actuate a valve (shear valves for example) but it is a bigger and more expensive solution.
Yet another solution has been the use of shape memory alloys that transform shape and/or size when heated. Shape memory alloys provide an advantage over the prior art solutions as they can typically be manufactured smaller and also generally consume less power. Although shape memory alloy actuated valves provide an advantage over traditional designs, there is a need for a shape memory alloy actuated valve that can be held in an actuated position without the continuous supply of power to the valve. The present invention overcomes this and other problems and an advance in the art is achieved. A shape memory alloy element is utilized in a valve where the shape memory alloy element can actuate the valve from a first position to a second position. Upon de-energizing the shape memory alloy element, the valve of the present invention is capable of retaining the new position. Therefore, the valve can stay in an actuated position without requiring a continuous supply of power.